Apparatus for regulating centrifugal machines



Sept. 7, 1948.

L. F; MOODY APPARATUS FOR REGLATING CENTRIFUGAL MACHINES Filed Aug. 30, 1946 3 4Sheets-Sheet l FIC-3.1

LEWIS F. MOODY IN VEN TOR.

FIG-2 L. F. MOODY Sept l7, 194s.

APPARATUS FOR REGULATING CENTRIFUGAL MACHINES Filed Aug. 50, 1946 5 Sheets-Sheet 2 .FIGJZ In "In '3 LEwls F. MOODY [Iv VEN TOR.

L. F. MOODY Sept. 7, 1948.

APPARATUSr FOR REGULATING CENTRIFUGAL MACHINES Filed Aug. 30, 1946 3 Sheets-Sheet 3 Fl GQ 7 vLEWIS F. MOODY INVENTOR.

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Patented Sept. 7, 1948 APPARATUS. FOR REGULATING CEN- i TRIFUGAL MACHINES ALewis F. Moody, Princeton, N. J. l; Y, Application Augustao, 194s, serial No; 693,995

The present invention effects the desired control or regulation of the head and capacity of a multi-stage centrifugal machine such as a pump orv compressor by throttling the now f fluid to the suction of one or more of the stages of the machine, and at the same time redirecting the flow into the suction chamber.

More specifically the present invention comprises the provision of one or more throttle valves in an inter-stage suction passage of a multistage machine, which when fully open permit full unimpeded normal 110W of iiuid through the suction passage and into the inlet of the impeller without material prerotation in the entering flow,

1 Claim. (Cl. 10S-97) centrifugal machine Ishowing modied forni of and which when p-artially closed to throttle down the quantity flow of uid to the impeller will shift the direction or distribution of ow of fluid into the inlet space of the impeller. This `is accomplished by directing the incoming flow transversely with yrespect to the axis of the im-` peller, or by laterally shifting the center of flow,

so as to produce unsymmetrical flow of the fluid and thereby set up prerotation in the entering fluid flow in the same direction as the impeller rotation. With progressive closure of the valve or valves the one-sided effect of the entering fluid flow is increased and its velocity is increased producing a vortex of continually increasing velocity towards its center and reduced quantity due to the unsymmetrical throttling action of the valve or throttle. The effect of such prerotation is to reduce the torque required to` drive the impeller by utilizing the velocity head produced by the valve throttling and thereby reduce the power required for operating the pump.

In the drawings:

Figure 1 is a view partly in section and partly in elevation of a multi-stage machine embodying the present invention.

Figure 2 is a cross-section taken on the line 2-2 of Figure 1. Y

Figure 3 is a fragmentary cross-section of 'a the throttling valve.` w n i y y Figure 4 is a cross-section taken on the linen 4-4 of FlgurejS.` N f u Figure 5 is a fragmntaryl-cross-section of a centrifugal machine showing` a still further vmod-y ied form of the valve-.f3- A Figure .6 is a fragmentary;cross-section through y a centrifugal machine illustrating a furtljiermodi-` fied structure of the throttling valve.l A

Figure "lis a cross-section oni` the line Figure 6. i Figure 8 is a `fragmentary `cross-section thrcugh a centrifugal machine illustrating aifurther typen.; of throttling valve. ,I l i; Figure 9 is a cross-section takenon the lill@ 9-9 of Figure 8. iM- Zggm l Figure` l0 `is `a vfragmentary. section 4through;` acentrifugal machine showing a combinedgrotary-t and slidable throttling valve structure.: d Figure 11 is a cross-sectiontaken on the line lI-ll of l'igurelil..` l Figure 12 is a cross-section through a centrii.-- 1 ugal machine having aV divided inlet passage and showinga plurality of throttling valves associated:. therewith. f 1 ,Y i Figure 13 is a verticalsectionthrough la lcenk trlfugal machine having a single inlet to5thel impeller thereof and .illustrating-larotarytype- L of throttling valve, and further takenorrfthey line l3--l3 of Figure' 14. Figure 14 is a fragmentary longitudinal se' c-.: tion through the form loft-centrifugal machinaV shown in Figure 1.3. l i ff Figure 15 is adetail vievvoijthe valve employed. in the construction of 'machine shown in ligure 13, and 14. n Referring :more particularly to the drawings a M multi-stage centrlfugalpump embodylngv-the in. .l vention` is'shown in Figure 1 of thedrawings; A` however it is to be understood that the inventionl` t may be applied to 'any'` type bf, multi-stage cen-yv trifugalfpurnp,` compressor, or yother analogous maehinewithout departing frbmvthespiritofthe l present invention'. i, v, The centrifugal lpump shown in Figures l1. al ,d 2 of the drawings comprises `a casing I whicmhas a plurality of stage chambers therein'rin which are4 rotatably mounted stagefimpellers v2.\ Ihefcasi ing` I' ifs provided withagstase passagelindieatedt; at V3 which corlYeysthe fluid `pumped fromthe'...` dischargei of; one stage tothe suctiornof-fthe-'suc-sr';r ceeding stage throughthe stagefinletA passage 4.,

The .present inventionl comprehends the` regu-` lation 'of the head and capa'cityof i.the .;pumpiby:i.

unsymmetrically throttling the inlet ow to one or more of the stage impellers of the pump or machine, preferably a stage or stages subsequent to the rst or inlet stage of the machine.

In Figures l and 2 of the drawings the inlet 5 passage 5 t-o the .controlled stage has a valve seat 6 formed therein with which a bulbv or needle type Valve 'l coeoperates, Thevalvel is.,-,adl`usltedby means ofaalrand wheel il. The passage 5 beyond the valvel opens into the suction chamber 8 10 The suction chamber. N

formed in the casing I. n 8 is formed as a space of revolution of somewhat' larger radius than the impeller eyeto accentuate,,1r4 the vortex flow provided by adjustmentpfsthe valve 1. l5

when the valve 1 is fully opened the fluid news' normally to the limpeller 2 without.any-apprenantE. g; ble prerotation in the entering flow, but. when? the valve 'l is Partly closed it will increase theu velocity alzongdthe enclosingN wall .of the suction 20 chambr 3Aso as'1to`produceiricreasing yltarylgential velocity components about .thepumpaxis'setup inane enteringnew' of uuid-inthesame .direction asttluie rotation of the mpeller 2. l'With'-progressivev closure of the valve `1theone-sidedverle-ct 25 of 'lilieadnissionfis increased and `iltsvelocity'is increasedl producing a verteiler-'continually inF cra'singvelcity-towards its f center and reduced quatitydue 'to' the i-tlf'nio'tA 'ing` actionof the-valve 1. 'Ijheeifcctfoffthprj citationA of theiluid is 30 to reduce luie torque reduiredftodrive the impeller by utilising the velocity head produced by the IveI thijottliiggv instead of. throwing gaway suchivel'city head as is; usual withf the throttling lof .thepurnp dischargeufor thepurpofse ofl con 35 trlii'ng" "its capacity; when pumpJi-ng'A-uquids the interzstagexthrottling control is preferably to be r "'rr'nore fthe'laterfaor nal stages gal -rnach`in rather Ytlianinl the cavitauon.- Trie valve 1 issn-series vi/untiefem- "s he needletypejofv 'valve shown in -IU as Ashownvin Figures 3 .and 4 of fthedrawings'l magasinage.; sneuvelen S11-iw asniablv .surpelfisd;assurabletensions'- I I carried b lie-casing i.,v The-'valve -I has a di- 2'; an by varyingthedegreeior proportionate A* part Y he pening'l! whlch'isopened fte the inlet passage thefiow of iiuidto the imp eller 2|- Tlisrllsirsilii-.Of iherivotl sf.. ihel'v'elve l5 165' ofi .the valvaA l t sturende the andgcapaclty-.zof icentrifugal szmacnine wheireim .75

s described n connection with 60 d sliding piston valve i7 is slidably supported in a valve cylinder i8. The valve cylinder I8 is positioned in the inlet passage converging into the inlet passage 2li. The inner ilow control end 2| of the valve l5 inclines diagonally from one edge -to the other so that when the valve Il is shifted it will first throttle and nally `cut off ythe flow oiuid through, the passage at `the right of the valve cylinder lil while permitting a greater fluid ow throughthe passage to the left of the valve cylinder, and thus causing an unsymmetrical flow of fluid entering' the suction chamber 8a of the -cenftritugalfimachine as set forth in connection 'with\ltlieidescription of the previous drawings. When the valve il has reached the bottom of its 'stroke 't'seats against the chamfered seat-ing surfaceshownfand completely cuts off the flow of iluid..

Figure's and 9 of the drawings show a horizontal slide valve 25 for throttling and directing the owfof Yfluidto the impeller 2b within the suc-tion 4chambler 8b.! The val-ve' 25 comprises a slidable plate v ihaving elongated opening 2l formed therein. ln this form the plate 25 is moved laterally across the inlet passage 5b serving -both to throttle' the fluid ilow and at the `same time shifting t'he center of ow to one side of the passage 5b -to provide the'l unsymmetrical, flow, and lvor-teX-iorniing Iprerotation desired for regulating the capacity oi the pump. In Figures l0 and l1 of the drawings the sliding valve structure 25 is replaced by la sliding cylindrical plug valve 23 pro-V vided-'with anelonga'ted orice 29 `by means of which. valvethe, )flow lt-o the inlet chamber lic and impeller 2c ispon-trolled or throttled and directed laterally to provide the unsymmetrical fluid now-.tothe impellerZc.

In Figure'lZ of the drawings the intake passage 5d is shown-as divided -by divider 3d into branches '3|' and 32' which enter the suction chamber 8d at opposite sid'e's of the axis of rota-tion of the impeller'VZd forming dual inlets to the suction cham bern` yEach ofthe branches 3i and 32 has a valve seat-Sftherein*which co-operates Awith valves 34 and' to Acontrolvthe flow through the branch passages.j Th`ej valves' 3ft and t5 are adjusted manually'-by suitable wheels 35.

When; both the valvesafl and 35 are opened as shownl Figure 12 of Ithe drawings a symmetrical l:normal flow into the suction chamber 8d Willlbe lprovided thus providing normal operation and avoiding prerotation in the iluid entering the suctiony or., inlet chamber 803. By iirst closing one of rthe valves, for instance the valve 34, all oi'fgthegfio'w of: the fluid entering the, iznpeIlerjZd Vis v'shifted-tto the branch 32 ,past the valve-`-35 which willvcause the fluid .to enter the suction'chamber lid in such manner as .to produce unsymrnetrical ilow `and thereby set up prerotation-inthe entering fluid flowl As the valve 35 is progressively closed for further-throttling the inletfoi iluidtothe inlet chamber 8d, .the-velocity vof the: entering iiuid vflow. is increased thereby` in- ,i lcreasing-the'prerotationlof the entering fluid and producrznfg@al vortex ofA continually increasing ve locitygaand lfreducedaquantity as -the valve 35 -is closed, untilsuch time-as the valve 35 is-completely closed when all ow to the inletof the impeller 2d ,will be shut olf. 4

FigureslB tolli inclusive of the drawings show a modification of the mannerA of control `of the headzand capacity of a multi-stage machine. In these'figures the inlet passage 5e is constructed and arranged so that the flow ofthe entering uid -is normally distributed symmetrically lto the impeller 2e. A rotary valve 4U which may be manually rotated by a suitable operating handle 4l extends across the inlet passage 5e and is prod vided with an elongated opening 42 the position of which controls the quantity of oW and consequently the throttling of the ilow of Huid into the suction space 8c of the impeller 2e. The valve 40 has an oiset port 43 formed therein, offset laterally from the elongated port 42v at one end of the valve. This offset port 43 cio-operates with the opening 42 in the valve so that when the elongated relatively narrow port 42 has been partially closed by rotating the valve 40, the oiset portion 43 Will still admit iluid to the chamber 8e giving a one sided admission of said fluid and cooperating with the offset passage 44 to provide prerotation and unsymmetrical flow to the incoming ui. By continuing the rotation of the valve the iiow through the valve may be cut off after the' offset port 43 is closed and thus provide complete closure.

When the principle of this invention is apiplied to blowers or compressors handling gaseous fluids, the unsymmetrical throttling means may be applied to a single-stage machine or to the :rst or suction stage of a multi-stage machine.

When however it is applied to pumps handling to be limited to the specic constructions or arrangements ef parts shown, but that they may be widely modified within the invention deflned by the claim.

What is claimed is:

in a multi-stage centrifugal pump for handling liquids subject to cavitation, the combination of a housing, a plurality of rotary stage impellers in said housing, said housing having suction and discharge passages connecting in fluid communication the discharge of the individual stages with the suction of the other stages, said housing having a rst suction passage for the iirst stage impeller, said suction passages except the first having needle valve seats therein, said seats being disposed so that fluid flowing therethrough is tangential to the impeller, needle valves cooperating with the seats to vary the effective cross section thereof, and means outside of the housing and connected to the valves for regulating the movements of the valves.

LEWIS F. MOODY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 928,034` Eickhoff July 13, 1909 FOREIGN PATENTS Number Country Date --fz--:w's-z-f'v': 

